New catalysts



Patented Aug. 9, 1932 UNITED STATES.

PATENT OFFICE ALFRED DIEBICH S, Q1 IEVERKUSEN-OlN-THE-BHINE, GERMANY,ASSIGNOR 1'0 I. G.

FARBENINDUSTRIE AKTIENGESELLSCEAFT, OF 'IRANKIOBT-ON-TH E-MAIN, GER-MANY ' NEW CATALYSTS I No Drawing. Original a ii aa nfaled'gtn ary 21,1930, Serial 1%. 422,879, and in Germany January as, 1929. Divided andthi rami lication'filed December 23,1930. Serial No. 504,413.

The present invention relates to new catalysts.

It is known that acetic anhydride is produced catalytically from glacialacetic acid; the technically important catalysts used therefor arealkali metal phosphates, especially secondary alkali metal phosphates,which sufierfrom the disadvantage that they react alkaline, whichalkaline reaction causes boric anhydride and phosphorus pentoxide-' obesides alkali metal salts, especially alkali the acetic acid to splitup into carbon, methmetal phosphates, have a much longer life than thecatalysts used heretofore. These new catalysts have the furtheradvantage that only little decomposition of the acetic acid by splittingoff of carbon is produced and that they can be readily regenerated byigniting in the air when after a long dura- .tion of catalyzation theybecome covered by carbon. The catalysts form white porous substanceswhich catalyze the production of anhydride) from aceticacid vapor atabout 400800 e. P

The preparation of the catalysts can be performed in the most simplemanner, for

example, by thoroughly heating a mixture of boron phosphate and analkali metal-salt for some time, say about one hour, at" between aboutGOO-900 0. Another way for preparing the catalysts is by dissolving thealkali metal salts in water them adding the boron phosphate, evaporatingto dryness on the water bath and calcining the substance tofabout'800-900? C. A clear melt is obthus obtained as described above.

As alkali metal salts I prefer to use phos phates, butalso carbonates,borates, hy-

, droxides and soonmay be usedwith the same i examples without beingrestricted thereefiect.

The invention is illustrated by the followabout- 700 and 750 C.

theory of acetic anhydride are obtained;

Example 1.--200 grams of acid sodium ammonium phosphate are dissolved in2 liters of water and 1 kg. of boron phosphate is added to the solution.After evaporating to dryness on the Water bath and then heating in acrucible to 700C; a porous white substance is obtained.

Acetic acid vapor is passed over this substance as a catalyst at GOO-620C. with a velocity of 1.5 kg. per hour. A yield of 48-50% of aceticanhydride is thus obtained calculated on the initial acetic acid.

Ewample'fZ.-100 grams of N a (N H.,) H.PO

and 100 grams of primary lithium phosphate are dissolved in 2 liters ofwater and to'this 1 kg. of boron phosphate is added. After evaporatingto dryness the product thus obtained is heated in a crucible to 700 C. Aporous white substance is obtained which, when used as a catalyst asdescribed in Example 1, leads to the same yield.

Example 3. 200 grams of borax are dissolved in 2 liters of water and 1kg. of boron phosphate is added. After evaporation, heating is efiectedto 700 C. A porous white product is obtained which is employed as acatalyst as describedin Example 1 with equal effect.- 7 I Example 4.100grams of sodium hydroxide and 100 grams of lithium hydroxide aredissolved'in 2 liters of water and 1 kg. of- ,boron .hosphateis added tothis solution,

therea r evaporation on the water bath takes place. The product is thencalcined at 1000 C. and a porous white product is obtained; This productis employed as-described in Example 1 and leads to the same yield.

Ea'sam Ze 5.-100 grams of finely-powdered boronp osphate,'100 grams ofely powdered sodium-meta-phosphate and 100 grams of finely powderedlithium-meta-phosphate are well mixed and heated for aboutl hour tained,which begins to soften at 450 0. and which is easily fusible above thistemperature.

' By passing acetic acid vapor through the molten catalyst attemperatures between 50v to of the This is a division of my copendingapplication Serial No. 422,379, filed J annary 21, Y 1930.

I claim 1. A catalyst consisting of at least one al kali metal salt andboron phosphate.

2. A catalyst consisting of at least one alkali metal phosphate andboron phosphate. p

3. A catalyst consisting of about equal parts of boron phosphate,sodium-meta-phosphate and lithium-meta-phosphate.

4. A catalyst consisting of at least one alkali metal borate and boronphosphate.

' 5. A catalyst consisting of Borax and boron phosphate.

6. A catalyst consistingof at least one alkali metal hydroxide and boronphosphate.

7. A catalyst consisting of sodium hydroxide, lithium hydroxide andboron phosphate.

In testimony whereof, I- aifix my signature.

ALFRED DIERIOHS.

